Molecuar basis of the development of GABAergic neuron using GFP knock-in mouse

点击翻译按钮获取中文摘要

In order to elucidate the molecular mechanisms of the development of GABAergic neurons, we labeled the GABAergic neurons with a reporter protein. First, we used transgenic mice to examine the expression pattern conferred by a 9.2-kb promoter-proximal DMA fragment of the glutamate decarboxylase (GAD) 65 gene fused to the bacterial /acZ reporter gene. Transgenic mice showed high β-galactosidase activity specifically in brain and testis. They also showed characteristic patterns of the transgene expression in olfactory bulb, cerebellar cortex and spinal cord, a similar expression pattern to that of endogenous GAD65. However, no transgene expression was observed in the ventral thalamus or hypothalamus, in which high GAD65 gene expression levels have been observed. These results suggest that the 9.2-kb DMA fragment of the GAD65 gene is associated with its tissue-specific expression and its targeted expression in GABAergic neurons of specific brain regions, but that additional regulatory elements are necessary to obtain fully correct expression. Second, we generated the GAD67-GFP mutant mice using knock-in method. In the GAD67-GFP mice, green fluorescence was observed in the GABAergic neurons without fixation. We utilized GAD67-GFP mice to observe distribution and migration of GABAergic neurons in the forebrain of the embryonic mouse. GFPpositve GABAergic neurons were found in the ganglionic eminences and the septum from Ell.5 and onwards. GABAergic neurons were also observed in the marginal zone and intermediate zone of the cortex. Using time-lapse imaging we observed that a large population of telencephalic GABAergic neurons migrate from the basal forebrain towards the cortex. These data suggest that GAD67-GFP mice will be useful for elucidating the development of GABAergic neurons.